Method to alter silicide properties using GCIB treatment

ABSTRACT

A method of manufacturing a semiconductor device is described. The method comprises performing a gas cluster ion beam (GCIB) pre-treatment and/or post-treatment of at least a portion of a silicon-containing substrate during formation of a silicide region.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 37 C.F.R. §1.78(a)(4), this application claims the benefitof and priority to U.S. Provisional Application No. 61/261,417, filed onNov. 16, 2009, which is expressly incorporated by reference herein inits entirety.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to a method for fabricating semiconductor devicesand, more particularly, a method for altering the material properties ofa silicide structure using a gas cluster ion beam (GCIB).

2. Description of Related Art

As the integration density of semiconductor devices continues toincrease and the critical dimensions associated with such devicescontinue to decrease, there has been a corresponding increase ininterest in identifying materials and processes for producing lowresistance materials that maintain or reduce signal delay. Silicide andsalicide (self-aligned silicide) materials and processes have beenwidely used to lower the sheet resistance and contact resistance for thegate conductor and source/drain regions of MOS devices.

A number of metals, including tungsten, tantalum, zirconium, titanium,hafnium, platinum, palladium, vanadium, niobium, cobalt, nickel andvarious alloys of such metals have been used to form silicide layers onsemiconductor devices. Nickel and nickel alloy, such as Ni(Pt), areattractive metals for forming silicides because the annealing processrequired to form the desired silicide may be conducted at a relativelylow temperature, e.g., below about 550 degrees C. (Celsius). Dependingon the reaction conditions, nickel can react with silicon to formdinickel monosilicide (Ni₂Si), nickel silicide (NiSi), or nickeldisilicide (NiSi₂), as the silicidation product. Nickel silicide (NiSi),however, provides the lowest sheet resistance of the three nickelsilicide phases.

Defectivity and thermal stability issues with NiSi and Ni(Pt)Si canlimit the performance, yield and/or reliability of advanced CMOSdevices. Many approaches have been used in the past to improvedefectivity and thermal stability issues, including pre-amorphizationimplant (PAI), pre-clean, ion implant of various species, andcomposition adjustment of deposited metal used to form the silicide.These approaches are generally aimed at modifying the formation kineticsand/or the thermal stability of the NiSi phase relative to the NiSi₂phase that can form defects and cause shorting. With many of theseapproaches, there are tradeoffs between yield/reliability andresistance/performance.

SUMMARY OF THE INVENTION

The invention relates to a method for fabricating semiconductor devicesand, more particularly, a method for altering the material properties ofa silicide structure using a gas cluster ion beam (GCIB).

According to one embodiment, a method for silicide formation on asubstrate is described. The method comprises: depositing ametal-containing layer over at least a portion of a silicon-containingsubstrate; irradiating the portion of the silicon-containing substratewith a GCIB following the depositing of the metal-containing layer; andreacting a portion of the metal-containing layer with the portion of thesilicon-containing substrate to form a silicide region, wherein thereacting proceeds before, during or after irradiating the portion of thesilicon-containing substrate with the GCIB.

According to another embodiment, a method for silicide formation on asubstrate is described. The method comprises irradiating at least aportion of a substrate with a GCIB to modify the portion of thesubstrate, which portion includes a SiGe or SiGeC region. The methodfurther comprises depositing a metal-containing layer over the portionof the substrate preceding the irradiating with the GCIB or followingthe irradiating with the GCIB, and reacting a portion of themetal-containing layer with the portion of the substrate to form asilicide region. The method further comprises increasing the proportionof silicon in the SiGe or SiGeC region using a Si-containing GCIBselected from said GCIB or another GCIB, and wherein increasing thesilicon proportion precedes the depositing, precedes the reacting, orfollows the reacting, or proceeds according to any combination thereof.

According to yet another embodiment, a silicidation process isdescribed. The method comprises preparing a substrate with aSiGe_(a)C_(b) region, wherein a is greater than 0, and b is greater thanor equal to 0. The method further comprises irradiating at least aportion of the SiGe_(a)C_(b) region with a GCIB to form a silicon-richsub-layer at a surface of the SiGe_(a)C_(b) region to a depth rangingfrom about 3 nm (nanometers) to about 30 nm, the silicon-rich sub-layerhaving the composition SiGe_(c)C_(d), wherein c is greater than or equalto 0 and less than a and 1, and wherein d is greater than or equal to 0and less than b and 1.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A through 1E illustrate a method for silicide formation;

FIGS. 2A through 2C illustrate methods for altering the properties ofsilicide formation according to several embodiments;

FIG. 3 is a flow chart illustrating a method of silicide formation on asubstrate according to another embodiment;

FIG. 4 is a flow chart illustrating a method of silicide formation on asubstrate according to another embodiment;

FIG. 5 is a flow chart illustrating a method of silicide formation on asubstrate according to yet another embodiment;

FIG. 6 is an illustration of a GCIB processing system;

FIG. 7 is another illustration of a GCIB processing system;

FIG. 8 is yet another illustration of a GCIB processing system;

FIG. 9 is an illustration of an ionization source for a GCIB processingsystem; and

FIG. 10 is an illustration of another ionization source for a GCIBprocessing system.

DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS

A method and system for silicide formation on a substrate using a gascluster ion beam (GCIB) is disclosed in various embodiments. However,one skilled in the relevant art will recognize that the variousembodiments may be practiced without one or more of the specificdetails, or with other replacement and/or additional methods, materials,or components. In other instances, well-known structures, materials, oroperations are not shown or described in detail to avoid obscuringaspects of various embodiments of the invention. Similarly, for purposesof explanation, specific numbers, materials, and configurations are setforth in order to provide a thorough understanding of the invention.Nevertheless, the invention may be practiced without specific details.Furthermore, it is understood that the various embodiments shown in thefigures are illustrative representations and are not necessarily drawnto scale.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, material, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the invention, but do not denote that theyare present in every embodiment. Thus, the appearances of the phrases“in one embodiment” or “in an embodiment” in various places throughoutthis specification are not necessarily referring to the same embodimentof the invention. Furthermore, the particular features, structures,materials, or characteristics may be combined in any suitable manner inone or more embodiments. Various additional layers and/or structures maybe included and/or described features may be omitted in otherembodiments.

“Substrate” as used herein generically refers to the object beingprocessed in accordance with the invention. The substrate may includeany material portion or structure of a device, particularly asemiconductor or other electronics device, and may, for example, be abase substrate structure, such as a semiconductor wafer or a layer on oroverlying a base substrate structure such as a thin film. Thus,substrate is not intended to be limited to any particular basestructure, underlying layer or overlying layer, patterned orunpatterned, but rather, is contemplated to include any such layer orbase structure, and any combination of layers and/or base structures.The description below may reference particular types of substrates, butthis is for illustrative purposes only and not limitation.

Referring now to the drawings wherein like reference numerals designatecorresponding parts throughout the several views, a method of forming asilicide layer for use in a semiconductor device is described in FIGS.1A through 1E according to several embodiments. The formation of thesilicide layer may include a salicide (self-aligned silicide) process.

As shown in FIG. 1A, the semiconductor device, generally referred to assubstrate 40, comprises a silicon-containing substrate 50 having a gatestructure 51 formed thereon and therein. The substrate 50 may comprisesingle crystal silicon, poly-crystalline silicon, silicon-germanium(SiGe_(x)) silicon-carbon (SiC_(y)), or silicon-germanium-carbon(SiGe_(x)C_(y)), or any combination of two or more thereof, and whereinx and y are greater than or equal to 0. The gate structure 51 includes agate electrode 52, a gate insulation layer 54, and a gate space layer53. The gate electrode 52 may include one or more layers including, forexample, one or more metal layers, one or more metal barrier layers, oneor more doped poly-crystalline silicon layers, and one or more caplayers. The gate insulation layer 54 may include, for example, aconventional gate dielectric, such as silicon dioxide (SiO₂), or a highdielectric constant (high-k) dielectric layer. The gate spacer layer 53may be composed of one or more material layers, including, for example,silicon oxide (SiO₂, or SiO_(x)) and/or silicon nitride (Si₃N₄, orSiN_(y)).

Also shown in FIG. 1A, the gate structure 51 further includeslightly-doped regions 55 and source/drain regions 56 formed in a surfaceregion of the silicon-containing substrate 50 using ion implant and/orGCIB infusion processes. Isolation regions 60 having silicide blockinglayers 61 may be formed adjacent the source/drain regions 56 to definethe active region of substrate 50 therebetween.

As shown in FIG. 1B, a metal-containing layer 70 is deposited oversilicon-containing substrate 50, including over the source/drain regions56 formed therein and over the portions of the gate structure 51 formedthereon. The metal-containing layer 70 may comprise tungsten, tantalum,zirconium, titanium, hafnium, platinum, palladium, vanadium, niobium,cobalt, nickel, or any alloy thereof. For example, the metal-containinglayer 70 may comprise nickel or a nickel alloy, such as anickel-platinum alloy. The metal-containing layer 70 may be depositedusing a vapor deposition process, such as a physical vapor deposition(PVD) process or variations thereof, a chemical vapor deposition (CVD)process or variations thereof, or an atomic layer deposition (ALD)process or variations thereof. For example, nickel or a nickel alloy maybe deposited using a PVD process. Prior to depositing themetal-containing layer 70, the substrate 40 may be cleaned using a dryand/or wet cleaning process to, for example, remove native oxide.Optionally, another metal-containing layer, such as titanium nitride(TiN) may be formed over the metal-containing layer 70.

Following the deposition of the metal-containing layer 70, as shown inFIG. 1C, a portion of the metal-containing layer 70 is reacted withunderlying portions of silicon-containing substrate 50 to form silicideregions 72. Specifically, in the embodiment shown, the portions of thesilicon-containing substrate 50 that underlie the metal-containing layer70 are the source/drain regions 56. Additionally, as shown, theunderlying gate electrode 52 may also react to form a silicide region72. The reaction between the metal-containing layer 70 and thesilicon-containing substrate 50 (and optionally the gate electrode 52)may proceed immediately following deposition, and may further include athermal process, such as a thermal anneal process. An un-reacted portion70 a of metal-containing layer 70 may remain.

As shown in FIG. 1D, upon formation of silicide regions 72, theun-reacted portion 70 a of the metal-containing layer 70 is removed fromsubstrate 40 and a dielectric layer 80 is deposited on substrate 40 toserve as inter-layer insulation. The un-reacted portion 70 a ofmetal-containing layer 70 may be removed from the substrate 40 using acleaning or etching process, such as a dry or wet etching/cleaningprocess. Additionally, following this removal, the substrate 40 may besubjected to another thermal process, such as a thermal anneal process.The dielectric layer 80 may be deposited using a vapor depositionprocess, such as a physical vapor deposition (PVD) process or variationsthereof, a chemical vapor deposition (CVD) or variations thereof, or anatomic layer deposition (ALD) process or variations thereof.

Thereafter, as shown in FIG. 1E, one or more via contacts 82 areprepared to expose contact surfaces 84. As shown, a contact surface 84may be the surface of a silicide region 72 formed in the surface portionof a source/drain region 56 of silicon-containing substrate 50. The oneor more via contacts 82 may be formed using a contact etch process, suchas a dry etching process and/or a wet etching process.

According to embodiments of the invention, at least one portion ofsilicon-containing substrate 50 is exposed to one or more GCIBtreatments before, during, or after any one of the process stepsdescribed in FIGS. 1A through 1E. The GCIB may be generated from apressurized gas mixture that includes He, Ne, Ar, Xe, Kr, B, C, Si, Ge,N, P, As, O, S, F, Cl, or Br, or any combination of two or more thereof.

According to one embodiment, at least one portion of silicon-containingsubstrate 50 of FIG. 1A is exposed to a GCIB 74 prior to deposition ofthe metal-containing layer 70, as shown in FIG. 2A, to enhance thesubsequent formation of the silicide regions 72. The GCIB treatment maybe utilized to modify, amorphize, and/or dope the exposed portion ofsilicon-containing substrate 50 to form mixed layer 75 having thickness76. The GCIB 74 may be generated from a pressurized gas mixture thatincludes He, Ne, Ar, Xe, Kr, B, C, Si, Ge, N, P, As, O, S, F, Cl, or Br,or any combination of two or more thereof. The GCIB treatment may reducedefectivity in the formation of silicide regions 72. For example, theGCIB treatment may promote silicide formation that is preferentiallycomposed of NiSi or Ni(Pt)Si. The GCIB treatment may amorphize theexposed portion of the silicon-containing substrate 50, or the GCIBtreatment may alter the composition at the exposed portion of thesilicon-containing substrate 50, or the GCIB treatment may amorphize andalter the composition at the exposed surface of the silicon-containingsubstrate 50. For example, the GCIB treatment may amorphize and/orincrease silicon content at the exposed surface of thesilicon-containing substrate 50, for example at the surface of thesource/drain regions 56.

In a further embodiment, where the portion of silicon-containingsubstrate 50 includes a SiGe or SiGeC region in which the silicide willbe formed, and where the GCIB 74 does not increase the silicon contentin that region prior to depositing the metal-containing layer 70,another GCIB containing Si may be used after depositing themetal-containing layer 70 and before or after reacting themetal-containing layer 70 with the portion of silicon-containingsubstrate 50 to increase the proportion of Si in the SiGe or SiGeCregion and thereby improve the silicide region formed therein.

According to another embodiment, at least one portion ofsilicon-containing substrate 50 of FIG. 1B is exposed to a GCIB 77following the deposition of the metal-containing layer 70, as shown inFIG. 2B, to enhance the formation of the silicide regions 72. The GCIBtreatment may be utilized to modify, amorphize, and/or dope the portionof substrate 50, which is underlying metal-containing layer 70, to formmixed layer 78 having thickness 79. The GCIB 77 may be generated from apressurized gas mixture that includes He, Ne, Ar, Xe, Kr, B, C, Si, Ge,N, P, As, O, S, F, Cl, or Br, or any combination of two or more thereof.The GCIB treatment may reduce defectivity in the formation of silicideregions 72. For example, the GCIB treatment may promote silicideformation that is preferentially composed of NiSi or Ni(Pt)Si. The GCIBmay amorphize the portion of the silicon-containing substrate 50, or theGCIB treatment may alter the composition at the portion of thesilicon-containing substrate 50, or the GCIB treatment may amorphize andalter the composition at the surface of the silicon-containing substrate50. For example, the GCIB may amorphize and/or increase silicon contentat the surface of the silicon-containing substrate 50, for example atthe surface of the source/drain regions 56.

According to yet another embodiment, at least one portion ofsilicon-containing substrate 50 is exposed to a GCIB 86 following theformation of the one or more via contacts 82 to expose contact surfaces84, which may be silicide regions 72. The GCIB treatment may be used toetch the contact surface 84, clean the contact surface 84, dope thecontact surface 84, modify the contact surface 84, deposit material onthe contact surface 84, or grow material on the contact surface 84, orany combination of two or more thereof. For example, the GCIB may begenerated from a pressurized gas mixture that includes He, Ne, Ar, Xe,Kr, B, C, Si, Ge, N, P, As, O, S, F, Cl, or Br, or any combination oftwo or more thereof.

Referring now to FIG. 3, a method for silicide formation on a substrateis described according to an embodiment. The method comprises a flowchart 1 beginning in 10 with irradiating at least a portion of asubstrate with a gas cluster ion beam (GCIB) to modify, amorphize,and/or dope the portion of the substrate. The substrate may comprisesingle crystal silicon, poly-crystalline silicon, silicon-germanium(SiGe_(x)), silicon-carbon (SiC_(y)), or silicon-germanium-carbon(SiGe_(x)C_(y)), or any combination of two or more thereof, and whereinx and y are greater than or equal to 0.

The GCIB may be generated from a pressurized gas mixture that includes anoble gas (i.e., He, Ne, Ar, Kr, Xe). Additionally, the GCIB may begenerated from a pressurized gas mixture that includes at least oneelement selected from the group consisting of He, Ne, Ar, Xe, Kr, B, C,Si, Ge, N, P, As, O, S, F, Cl, and Br. For example, the GCIB may includeSi to increase silicon content at the portion of the substrate.

The GCIB may be used to form a mixed layer having a pre-determinedthickness in the substrate. The mixed layer may be amorphous and promotegreater penetration of the reaction between the metal-containing layerand the substrate. Additionally, the mixed layer may include one or moredopants and/or impurities infused using the GCIB. Furthermore, the mixedlayer may include a concentration profile extending partly or fullythrough the mixed layer that is tailored via adjustment of one or moreGCIB processing parameters of the GCIB.

In addition to irradiation of the substrate with the GCIB in 10, anotherGCIB may be used for additional control and/or function. Irradiation ofthe substrate by another GCIB may proceed before, during, or after useof the GCIB in 10. For example, another GCIB may be used to dope theportion of the substrate with an impurity. The doping may compriseintroducing one or more elements selected from the group consisting ofHe, Ne, Ar, Xe, Kr, B, C, Si, Ge, N, P, As, O, S, F, Cl, and Br. Forexample, the another GCIB may include Si to increase silicon content atthe portion of the substrate.

The portion of the substrate subjected to GCIB irradiation may becleaned before or after the irradiating with the GCIB in 10. Forexample, the cleaning process may include a dry cleaning process and/ora wet cleaning process. Additionally, the portion of the substratesubjected to GCIB irradiation may be annealed after the irradiating withthe GCIB in 10.

In 11, a metal-containing layer is deposited over the portion of thesubstrate following the irradiating with the GCIB in 10. Themetal-containing layer may comprise tungsten, tantalum, zirconium,titanium, hafnium, platinum, palladium, vanadium, niobium, cobalt,nickel, or any alloy thereof. For example, the metal-containing layermay comprise nickel or a nickel alloy, such as nickel-platinum. Prior todepositing the metal-containing layer, the substrate may be cleanedusing a dry and/or wet cleaning process to, for example, remove nativeoxide. Optionally, another metal-containing layer, such as titaniumnitride (TiN) may be formed over the metal-containing layer.

In addition to irradiation of the substrate with the GCIB in 10, yetanother GCIB may be used following the deposition of themetal-containing layer in 11. For example, the composition of the GCIBand/or one or more GCIB processing parameters may be tailored to modifya surface layer of the substrate and/or dope the substrate with animpurity.

In 12, a portion of the metal-containing layer is reacted with theportion of the substrate to form a silicide region. The reaction of themetal-containing layer with the substrate may comprise performing athermal anneal process.

In addition to irradiation of the substrate with the GCIB in 10, yetanother GCIB may be used to infuse material into the substrate followingthe deposition of the metal-containing layer in 11 and/or following thereacting of the metal-containing layer with the substrate in 12. Forexample, the another GCIB may include Si to increase silicon content atthe portion of the substrate.

Thereafter, an un-reacted portion of the metal-containing layer isremoved from the substrate following the reaction of the portion of themetal-containing layer with the substrate in 12. The removal of theun-reacted portion may be performed using a dry and/or wetcleaning/etching process. Following the removing, the substrate may beannealed using a thermal anneal process. A dielectric layer is formed onthe substrate over the silicide region, and a contact etch process isperformed above the silicide region to open a contact via through thedielectric layer to a contact surface of the silicide region.

The contact surface of the contact via may be irradiated with anotherGCIB to etch the contact surface, clean the contact surface, dope thecontact surface, modify the contact surface, deposit material on thecontact surface, or grow material on the contact surface, or anycombination of two or more thereof.

Referring now to FIG. 4, a method for silicide formation on a substrateis described according to another embodiment. The method comprises aflow chart 2 beginning in 20 with depositing a metal-containing layerover at least a portion of a substrate. The substrate may comprisesingle crystal silicon, poly-crystalline silicon, silicon-germanium(SiGe_(x)), silicon-carbon (SiC_(y)), or silicon-germanium-carbon(SiGe_(x)C_(y)), or any combination of two or more thereof, and whereinx and y are greater than or equal to 0. The metal-containing layer maycomprise tungsten, tantalum, zirconium, titanium, hafnium, platinum,palladium, vanadium, niobium, cobalt, nickel, or any alloy thereof. Forexample, the metal-containing layer may comprise nickel or a nickelalloy, such as nickel-platinum. Prior to depositing the metal-containinglayer, the substrate may be cleaned using a dry and/or wet cleaningprocess to, for example, remove native oxide. Optionally, anothermetal-containing layer, such as titanium nitride (TiN) may be formedover the metal-containing layer.

In 21, the portion of the substrate is irradiated with a gas cluster ionbeam (GCIB). The GCIB may be generated from a pressurized gas mixturethat includes a noble gas (i.e., He, Ne, Ar, Kr, Xe). Additionally, theGCIB may be generated from a pressurized gas mixture that includes atleast one element selected from the group consisting of He, Ne, Ar, Xe,Kr, B, C, Si, Ge, N, P, As, O, S, F, Cl, and Br. For example, the GCIBmay include Si to increase silicon content at the portion of thesubstrate.

The GCIB may be used to form a mixed layer having a pre-determinedthickness in the substrate. The mixed layer may be amorphous and promotegreater penetration of the reaction between the metal-containing layerand the substrate. Additionally, the mixed layer may include one or moredopants and/or impurities infused using the GCIB. Furthermore, the mixedlayer may include a concentration profile extending partly or fullythrough the mixed layer that is tailored via adjustment of one or moreGCIB processing parameters of the GCIB.

In addition to irradiation of the substrate with the GCIB in 21, anotherGCIB may be used for additional control and/or function. Irradiation ofthe substrate by another GCIB may proceed before, during, or after useof the GCIB in 21. For example, another GCIB may be used to dope theportion of the substrate with an impurity. The doping may compriseintroducing one or more elements selected from the group consisting ofHe, Ne, Ar, Xe, Kr, B, C, Si, Ge, N, P, As, O, S, F, Cl, and Br. Forexample, the GCIB may include Si to increase silicon content at theportion of the substrate.

The portion of the substrate subjected to GCIB irradiation may becleaned before or after the irradiating with the GCIB in 21. Forexample, the cleaning process may include a dry cleaning process and/ora wet cleaning process. Additionally, the portion of the substratesubjected to GCIB irradiation may be annealed after the irradiating withthe GCIB in 21.

In addition to irradiation of the substrate with the GCIB in 21, yetanother GCIB may be used preceding the deposition of themetal-containing layer in 20. For example, the composition of the GCIBand/or one or more GCIB processing parameters may be tailored to modifya surface layer of the substrate, or dope the substrate with animpurity. For example, the another GCIB may include Si to increasesilicon content at the portion of the substrate. Additionally, forexample, the another GCIB may include a noble gas element to amorphizethe portion of the substrate.

In 22, a portion of the metal-containing layer is reacted with theportion of the substrate to form a silicide region. The reaction of themetal-containing layer with the substrate may comprise performing athermal anneal process. Additionally, the reaction in 22 may proceedbefore, during or after the irradiating of the portion of the substratewith the GCIB in 21.

In addition to irradiation of the substrate with the GCIB in 21, yetanother GCIB may be used to infuse material into the substrate followingthe reacting of the metal-containing layer with the substrate in 22. Forexample, the another GCIB may include Si to increase silicon content atthe portion of the substrate.

Thereafter, an un-reacted portion of the metal-containing layer isremoved from the substrate following the reaction of the portion of themetal-containing layer with the substrate in 22. The removal of theun-reacted portion may be performed using a dry and/or wetcleaning/etching process. Following the removing, the substrate may beannealed using a thermal anneal process. A dielectric layer is formed onthe substrate over the silicide region, and a contact etch process isperformed above the silicide region to open a contact via through thedielectric layer to a contact surface of the silicide region.

The contact surface of the contact via may be irradiated with anotherGCIB to etch the contact surface, clean the contact surface, dope thecontact surface, modify the contact surface, deposit material on thecontact surface, or grow material on the contact surface, or anycombination of two or more thereof.

Referring now to FIG. 5, a silicidation process for silicide formationon a substrate is described according to yet another embodiment. Themethod comprises a flow chart 3 beginning in 30 with preparing asubstrate with a SiGe_(a)C_(b) region, wherein a is greater than 0, andb is greater than or equal to 0.

In 31, at least a portion of the SiGe_(a)C_(b) region is irradiated witha gas cluster ion beam (GCIB) to form a silicon-rich sub-layer at asurface of the SiGe_(a)C_(b) region. The irradiation may proceed to formthe silicon-rich sub-layer to a depth ranging from about 3 nm to about30 nm. The silicon-rich sub-layer has the composition SiGe_(c)C_(d),wherein c is greater than or equal to 0 and less than a and 1, andwherein d is greater than or equal to 0 and less than b and 1.

The inventors believe that increasing silicon content (i.e., increasingthe proportion of Si in SiGe or SiGeC) at a surface portion of thesubstrate improves the thermal stability of SiGe_(a)C_(b)-silicides,such as SiGe_(a)-silicides (where b is zero). The temperature stabilityof SiGe_(a)C_(b)-silicides degrades with increased Ge concentration.Therefore, a GCIB may be used to infuse silicon in the surface layer ofthe substrate to produce a silicon-rich sub-layer. This infusion processmay precede the formation of a silicide layer or follow the formation ofthe silicide layer.

The GCIB may be generated from a pressurized gas mixture that includesSi. For example, the GCIB may be generated from a pressurized gasmixture that includes silane, disilane, an alkyl silane, an alkanesilane, an alkene silane, an alkyne silane, methylsilane (H₃C—SiH₃),dimethylsilane (H₃C—SiH₂—CH₃), trimethylsilane ((CH₃)₃—SiH), ortetramethylsilane ((CH₃)₄—Si), or any combination of two or morethereof. Additionally, the GCIB may further include one or more elementsselected from the group consisting of He, Ne, Ar, Xe, Kr, B, C, Ge, N,P, As, O, S, F, Cl, and Br.

A cleaning step and/or an annealing step may be inserted before or afterany one of the process steps described above.

As described above, one or more GCIB treatments may be performed tomodify and/or enhance a material property of a substrate during asilicide process. For any one of these GCIB treatments, a GCIB operationmay comprise: establishing a GCIB; selecting a beam energy, a beamenergy distribution, a beam focus, and a beam dose; accelerating theGCIB to achieve the beam energy; focusing the GCIB to achieve the beamfocus; and exposing the portion of the substrate to the accelerated GCIBaccording to the beam dose. The GCIB treatment may further compriseselecting the beam energy and the beam dose to achieve a desiredthickness of a mixed layer formed during irradiating the portion of thesubstrate with the GCIB.

A GCIB may be established having an energy per atom ratio ranging fromabout 0.25 eV per atom to about 100 eV per atom. Alternatively, the GCIBmay be established having an energy per atom ratio ranging from about0.25 eV per atom to about 10 eV per atom. Alternatively, the GCIB may beestablished having an energy per atom ratio ranging from about 1 eV peratom to about 10 eV per atom. The GCIB can be formed in a GCIBprocessing system, such as any of the GCIB processing systems (100, 100′or 100″) described below in FIG. 5, 6 or 7, or any combination thereof.

The substrate to be treated may be provided in a reduced-pressureenvironment in a GCIB processing system. The substrate may be positionedon a substrate holder and may be securely held by the substrate holder.The temperature of the substrate may or may not be controlled. Forexample, the substrate may be heated or cooled during a film formingprocess. The environment surrounding the substrate is maintained at areduced pressure.

A GCIB may be generated in the reduced-pressure environment, and can begenerated from a pressurized gas mixture. The pressurized gas mixturemay use a material source comprising one or more gases containingelements selected from the group consisting of He, Ne, Ar, Kr, Xe, B, C,Si, Ge, N, P, As, O, S, F, and Cl. For example, the material source maycomprise He, Ne, Ar, Kr, Xe, SiH₄, Si₂H₆, SiH₂Cl₂, SiCl₃H, methylsilane,dimethylsilane, trimethylsilane, tetramethylsilane, ethylsilane,diethylsilane, triethylsilane, tetraethylsilane, SiCl₄, SiF₄, GeH₄,Ge₂H₆, GeH₂Cl₂, GeCl₃H, methylgermane, dimethylgermane,trimethylgermane, tetramethylgermane, ethylgermane, diethylgermane,triethylgermane, tetraethylgermane, GeCl₄, GeF₄, N₂, H₂, O₂, NO, NO₂,N₂O, NH₃, NF₃, HCl, SF₆, CO, CO₂, C₂H₄, CH₄, C₂H₂, C₂H₆, C₃H₄, C₃H₆,C₃H₈, C₄H₆, C₄H₈, C₄H₁₀, C₅H₈, C₅H₁₀, C₆H₆, C₆H₁₀, C₆H₁₂, BF₃, B₂H₆,AsH₃, AsF₅, PH₃, PF₃, PCl₃, or PF₅, or any combination of two or morethereof.

A beam acceleration potential, a beam dose, and/or a cluster size can beselected. The beam acceleration potential, the beam dose, and/or thecluster size can be selected to achieve pre-specified properties of thesubstrate. For example, the beam acceleration potential, cluster size,and/or beam dose may be adjusted to alter the material properties of thesubstrate, i.e., as will be described below, alter a concentration ofone or more species within the substrate, a concentration profile of oneor more species within the substrate, or depth of one or more specieswithin the substrate, or any combination thereof. The beam accelerationpotential may range up to 100 kV, the cluster size may range up toseveral tens of thousands of atoms, and the beam dose may range up toabout 1×10¹⁷ clusters per cm². For example, the beam accelerationpotential may range from about 1 kV to about 70 kV (i.e., the beamenergy may range from about 1 keV to about 70 keV). Additionally, forexample, the beam dose may range from about 1×10¹⁵ clusters per cm² toabout 1×10¹⁷ clusters per cm².

The beam acceleration potential may be used to modify the depth ofpenetration of the one or more elements in the substrate, i.e.,increasing the beam acceleration potential increases the depth anddecreasing the beam acceleration potential decreases the depth.Additionally, the beam dose may be used to modify the concentration ofthe one or more elements in the substrate, i.e., increasing the beamdose increases the final concentration and decreasing the beam dosedecrease the final concentration. The GCIB is accelerated according tothe beam acceleration potential, and the substrate is exposed to theGCIB according to the beam dose.

Herein, beam dose is given the units of number of clusters per unitarea. However, beam dose may also include beam current and/or time(e.g., GCIB dwell time). For example, the beam current may be measuredand maintained constant, while time is varied to change the beam dose.Alternatively, for example, the rate at which clusters strike thesurface of the substrate per unit area (i.e., number of clusters perunit area per unit time) may be held constant while the time is variedto change the beam dose.

Furthermore, the energy per atom ratio may be used to adjust theconcentration of one or more elements present or not present in thematerial layer and/or the depth to which the one or more elements arepresent in the material layer. For instance, while decreasing the energyper atom ratio, the adjusted depth may be decreased. Alternatively,while increasing the energy per atom ratio, the adjusted depth may beincreased.

The establishment of the GCIB having a desired energy per atom ratio mayinclude selection of a beam acceleration potential, a stagnationpressure for formation of the GCIB, or a gas flow rate, or anycombination thereof. The beam acceleration potential may be used toincrease or decrease the beam energy or energy per ion cluster. Forexample, an increase in the beam acceleration potential causes anincrease in the maximum beam energy and, consequently, an increase inthe energy per atom ratio for a given cluster size. Additionally, thestagnation pressure may be used to increase or decrease the cluster sizefor a given cluster. For example, an increase in the stagnation pressureduring formation of the GCIB causes an increase in the cluster size(i.e., number of atoms per cluster) and, consequently, a decrease in theenergy per atom ratio for a given beam acceleration potential.

Additionally yet, other GCIB properties may be varied to adjust theamorphizing, doping or modification of the substrate including, but notlimited to, beam energy distribution, cluster size distribution, or gasnozzle design (such as nozzle throat diameter, nozzle length, and/ornozzle divergent section half-angle).

Furthermore, as described above, one or more thermal anneals may beperformed to modify and/or enhance a material property of a substrateduring a silicide process. For any one of these thermal anneals, thesubstrate may be subjected to a thermal treatment, wherein thetemperature of the substrate is elevated to a material-specifictemperature for a period of time. The temperature and the time for theannealing process may be adjusted in order to vary the properties of thesubstrate. For example, the temperature of the substrate may be elevatedto a value greater than about 800 degrees C. Additionally, for example,the temperature of the substrate may be elevated to a value greater thanabout 850 degrees C. Additionally yet, for example, the temperature ofthe substrate may be elevated to a value greater than about 900 degreesC. Furthermore, for example, the time for the annealing process may begreater than about 1 millisecond. The annealing process may be performedat atmospheric pressure or reduced pressure. Additionally, the annealingprocess may be performed with or without an inert gas atmosphere.Furthermore, the annealing process may be performed in a furnace, arapid thermal annealing (RTP) system, a flash lamp annealing system, ora laser annealing system.

Referring now to FIG. 6, a GCIB processing system 100 for treating asubstrate as described above is depicted according to an embodiment. TheGCIB processing system 100 comprises a vacuum vessel 102, substrateholder 150, upon which a substrate 152 to be processed is affixed, andvacuum pumping systems 170A, 170B, and 170C. Substrate 152 can be asemiconductor substrate, a wafer, a flat panel display (FPD), a liquidcrystal display (LCD), or any other workpiece. GCIB processing system100 is configured to produce a GCIB for treating substrate 152.

Referring still to GCIB processing system 100 in FIG. 6, the vacuumvessel 102 comprises three communicating chambers, namely, a sourcechamber 104, an ionization/acceleration chamber 106, and a processingchamber 108 to provide a reduced-pressure enclosure. The three chambersare evacuated to suitable operating pressures by vacuum pumping systems170A, 170B, and 170C, respectively. In the three communicating chambers104, 106, 108, a gas cluster beam can be formed in the first chamber(source chamber 104), while a GCIB can be formed in the second chamber(ionization/acceleration chamber 106) wherein the gas cluster beam isionized and accelerated. Then, in the third chamber (processing chamber108), the accelerated GCIB may be utilized to treat substrate 152.

Although specific examples are provided for transistor gate and trenchcapacitor applications, the methods of etching, as described above, maybe utilized in any substrate processing wherein etching is necessitated.

As shown in FIG. 6, GCIB processing system 100 can comprise one or moregas sources configured to introduce one or more gases or mixture ofgases to vacuum vessel 102. For example, a first gas composition storedin a first gas source 111 is admitted under pressure through a first gascontrol valve 113A to a gas metering valve or valves 113. Additionally,for example, a second gas composition stored in a second gas source 112is admitted under pressure through a second gas control valve 113B tothe gas metering valve or valves 113. Further, for example, the firstgas composition or second gas composition or both can include acondensable inert gas, carrier gas or dilution gas. For example, theinert gas, carrier gas or dilution gas can include a noble gas, i.e.,He, Ne, Ar, Kr, Xe, or Rn.

Furthermore, the first gas source 111 and the second gas source 112 maybe utilized either alone or in combination with one another to produceionized clusters. The material composition can include the principalatomic or molecular species of the elements desired to be introduced tothe material layer.

The high pressure, condensable gas comprising the first gas compositionor the second gas composition or both is introduced through gas feedtube 114 into stagnation chamber 116 and is ejected into thesubstantially lower pressure vacuum through a properly shaped nozzle110. As a result of the expansion of the high pressure, condensable gasfrom the stagnation chamber 116 to the lower pressure region of thesource chamber 104, the gas velocity accelerates to supersonic speedsand gas cluster beam 118 emanates from nozzle 110.

The inherent cooling of the jet as static enthalpy is exchanged forkinetic energy, which results from the expansion in the jet, causes aportion of the gas jet to condense and form a gas cluster beam 118having clusters, each consisting of from several to several thousandweakly bound atoms or molecules. A gas skimmer 120, positioneddownstream from the exit of the nozzle 110 between the source chamber104 and ionization/acceleration chamber 106, partially separates the gasmolecules on the peripheral edge of the gas cluster beam 118, that maynot have condensed into a cluster, from the gas molecules in the core ofthe gas cluster beam 118, that may have formed clusters. Among otherreasons, this selection of a portion of gas cluster beam 118 can lead toa reduction in the pressure in the downstream regions where higherpressures may be detrimental (e.g., ionizer 122, and processing chamber108). Furthermore, gas skimmer 120 defines an initial dimension for thegas cluster beam entering the ionization/acceleration chamber 106.

After the gas cluster beam 118 has been formed in the source chamber104, the constituent gas clusters in gas cluster beam 118 are ionized byionizer 122 to form GCIB 128. The ionizer 122 may include an electronimpact ionizer that produces electrons from one or more filaments 124,which are accelerated and directed to collide with the gas clusters inthe gas cluster beam 118 inside the ionization/acceleration chamber 106.Upon collisional impact with the gas cluster, electrons of sufficientenergy eject electrons from molecules in the gas clusters to generateionized molecules. The ionization of gas clusters can lead to apopulation of charged gas cluster ions, generally having a net positivecharge.

As shown in FIG. 6, beam electronics 130 are utilized to ionize,extract, accelerate, and focus the GCIB 128. The beam electronics 130include a filament power supply 136 that provides voltage V_(F) to heatthe ionizer filament 124.

Additionally, the beam electronics 130 include a set of suitably biasedhigh voltage electrodes 126 in the ionization/acceleration chamber 106that extracts the cluster ions from the ionizer 122. The high voltageelectrodes 126 then accelerate the extracted cluster ions to a desiredenergy and focus them to define GCIB 128. The kinetic energy of thecluster ions in GCIB 128 typically ranges from about 1000 electron volts(1 keV) to several tens of keV. For example, GCIB 128 can be acceleratedto 1 to 100 keV.

As illustrated in FIG. 6, the beam electronics 130 further include ananode power supply 134 that provides voltage V_(A) to an anode ofionizer 122 for accelerating electrons emitted from filament 124 andcausing the electrons to bombard the gas clusters in gas cluster beam118, which produces cluster ions.

Additionally, as illustrated in FIG. 6, the beam electronics 130 includean extraction power supply 138 that provides voltage V_(EE) to bias atleast one of the high voltage electrodes 126 to extract ions from theionizing region of ionizer 122 and to form the GCIB 128. For example,extraction power supply 138 provides a voltage to a first electrode ofthe high voltage electrodes 126 that is less than or equal to the anodevoltage of ionizer 122.

Furthermore, the beam electronics 130 can include an accelerator powersupply 140 that provides voltage V_(ACC) to bias one of the high voltageelectrodes 126 with respect to the ionizer 122 so as to result in atotal GCIB acceleration energy equal to about V_(ACC) electron volts(eV). For example, accelerator power supply 140 provides a voltage to asecond electrode of the high voltage electrodes 126 that is less than orequal to the anode voltage of ionizer 122 and the extraction voltage ofthe first electrode.

Further yet, the beam electronics 130 can include lens power supplies142, 144 that may be provided to bias some of the high voltageelectrodes 126 with potentials (e.g., V_(L1) and V_(L2)) to focus theGCIB 128. For example, lens power supply 142 can provide a voltage to athird electrode of the high voltage electrodes 126 that is less than orequal to the anode voltage of ionizer 122, the extraction voltage of thefirst electrode, and the accelerator voltage of the second electrode,and lens power supply 144 can provide a voltage to a fourth electrode ofthe high voltage electrodes 126 that is less than or equal to the anodevoltage of ionizer 122, the extraction voltage of the first electrode,the accelerator voltage of the second electrode, and the first lensvoltage of the third electrode.

Note that many variants on both the ionization and extraction schemesmay be used. While the scheme described here is useful for purposes ofinstruction, another extraction scheme involves placing the ionizer andthe first element of the extraction electrode(s) (or extraction optics)at V_(ACC). This typically requires fiber optic programming of controlvoltages for the ionizer power supply, but creates a simpler overalloptics train. The invention described herein is useful regardless of thedetails of the ionizer and extraction lens biasing.

A beam filter 146 in the ionization/acceleration chamber 106 downstreamof the high voltage electrodes 126 can be utilized to eliminatemonomers, or monomers and light cluster ions from the GCIB 128 to definea filtered process GCIB 128A that enters the processing chamber 108. Inone embodiment, the beam filter 146 substantially reduces the number ofclusters having 100 or less atoms or molecules or both. The beam filtermay comprise a magnet assembly for imposing a magnetic field across theGCIB 128 to aid in the filtering process.

Referring still to FIG. 6, a beam gate 148 is disposed in the path ofGCIB 128 in the ionization/acceleration chamber 106. Beam gate 148 hasan open state in which the GCIB 128 is permitted to pass from theionization/acceleration chamber 106 to the processing chamber 108 todefine process GCIB 128A, and a closed state in which the GCIB 128 isblocked from entering the processing chamber 108. A control cableconducts control signals from control system 190 to beam gate 148. Thecontrol signals controllably switch beam gate 148 between the open orclosed states.

A substrate 152, which may be a wafer or semiconductor wafer, a flatpanel display (FPD), a liquid crystal display (LCD), or other substrateto be processed by GCIB processing, is disposed in the path of theprocess GCIB 128A in the processing chamber 108. Because mostapplications contemplate the processing of large substrates withspatially uniform results, a scanning system may be desirable touniformly scan the process GCIB 128A across large areas to producespatially homogeneous results.

An X-scan actuator 160 provides linear motion of the substrate holder150 in the direction of X-scan motion (into and out of the plane of thepaper). A Y-scan actuator 162 provides linear motion of the substrateholder 150 in the direction of Y-scan motion 164, which is typicallyorthogonal to the X-scan motion. The combination of X-scanning andY-scanning motions translates the substrate 152, held by the substrateholder 150, in a raster-like scanning motion through process GCIB 128Ato cause a uniform (or otherwise programmed) irradiation of a surface ofthe substrate 152 by the process GCIB 128A for processing of thesubstrate 152.

The substrate holder 150 disposes the substrate 152 at an angle withrespect to the axis of the process GCIB 128A so that the process GCIB128A has an angle of beam incidence 166 with respect to a substrate 152surface. The angle of beam incidence 166 may be 90 degrees or some otherangle, but is typically 90 degrees or near 90 degrees. DuringY-scanning, the substrate 152 and the substrate holder 150 move from theshown position to the alternate position “A” indicated by thedesignators 152A and 150A, respectively. Notice that in moving betweenthe two positions, the substrate 152 is scanned through the process GCIB128A, and in both extreme positions, is moved completely out of the pathof the process GCIB 128A (over-scanned). Though not shown explicitly inFIG. 5, similar scanning and over-scan is performed in the (typically)orthogonal X-scan motion direction (in and out of the plane of thepaper).

A beam current sensor 180 may be disposed beyond the substrate holder150 in the path of the process GCIB 128A so as to intercept a sample ofthe process GCIB 128A when the substrate holder 150 is scanned out ofthe path of the process GCIB 128A. The beam current sensor 180 istypically a faraday cup or the like, closed except for a beam-entryopening, and is typically affixed to the wall of the vacuum vessel 102with an electrically insulating mount 182.

As shown in FIG. 6, control system 190 connects to the X-scan actuator160 and the Y-scan actuator 162 through electrical cable and controlsthe X-scan actuator 160 and the Y-scan actuator 162 in order to placethe substrate 152 into or out of the process GCIB 128A and to scan thesubstrate 152 uniformly relative to the process GCIB 128A to achievedesired processing of the substrate 152 by the process GCIB 128A.Control system 190 receives the sampled beam current collected by thebeam current sensor 180 by way of an electrical cable and, thereby,monitors the GCIB and controls the GCIB dose received by the substrate152 by removing the substrate 152 from the process GCIB 128A when apredetermined dose has been delivered.

In the embodiment shown in FIG. 7, the GCIB processing system 100′ canbe similar to the embodiment of FIG. 6 and further comprise a X-Ypositioning table 253 operable to hold and move a substrate 252 in twoaxes, effectively scanning the substrate 252 relative to the processGCIB 128A. For example, the X-motion can include motion into and out ofthe plane of the paper, and the Y-motion can include motion alongdirection 264.

The process GCIB 128A impacts the substrate 252 at a projected impactregion 286 on a surface of the substrate 252, and at an angle of beamincidence 266 with respect to the surface of substrate 252. By X-Ymotion, the X-Y positioning table 253 can position each portion of asurface of the substrate 252 in the path of process GCIB 128A so thatevery region of the surface may be made to coincide with the projectedimpact region 286 for processing by the process GCIB 128A. An X-Ycontroller 262 provides electrical signals to the X-Y positioning table253 through an electrical cable for controlling the position andvelocity in each of X-axis and Y-axis directions. The X-Y controller 262receives control signals from, and is operable by, control system 190through an electrical cable. X-Y positioning table 253 moves bycontinuous motion or by stepwise motion according to conventional X-Ytable positioning technology to position different regions of thesubstrate 252 within the projected impact region 286. In one embodiment,X-Y positioning table 253 is programmably operable by the control system190 to scan, with programmable velocity, any portion of the substrate252 through the projected impact region 286 for GCIB processing by theprocess GCIB 128A.

The substrate holding surface 254 of positioning table 253 iselectrically conductive and is connected to a dosimetry processoroperated by control system 190. An electrically insulating layer 255 ofpositioning table 253 isolates the substrate 252 and substrate holdingsurface 254 from the base portion 260 of the positioning table 253.Electrical charge induced in the substrate 252 by the impinging processGCIB 128A is conducted through substrate 252 and substrate holdingsurface 254, and a signal is coupled through the positioning table 253to control system 190 for dosimetry measurement. Dosimetry measurementhas integrating means for integrating the GCIB current to determine aGCIB processing dose. Under certain circumstances, a target-neutralizingsource (not shown) of electrons, sometimes referred to as electronflood, may be used to neutralize the process GCIB 128A. In such case, aFaraday cup (not shown, but which may be similar to beam current sensor180 in FIG. 6) may be used to assure accurate dosimetry despite theadded source of electrical charge, the reason being that typical Faradaycups allow only the high energy positive ions to enter and be measured.

In operation, the control system 190 signals the opening of the beamgate 148 to irradiate the substrate 252 with the process GCIB 128A. Thecontrol system 190 monitors measurements of the GCIB current collectedby the substrate 252 in order to compute the accumulated dose receivedby the substrate 252. When the dose received by the substrate 252reaches a predetermined dose, the control system 190 closes the beamgate 148 and processing of the substrate 252 is complete. Based uponmeasurements of the GCIB dose received for a given area of the substrate252, the control system 190 can adjust the scan velocity in order toachieve an appropriate beam dwell time to treat different regions of thesubstrate 252.

Alternatively, the process GCIB 128A may be scanned at a constantvelocity in a fixed pattern across the surface of the substrate 252;however, the GCIB intensity is modulated (may be referred to as Z-axismodulation) to deliver an intentionally non-uniform dose to the sample.The GCIB intensity may be modulated in the GCIB processing system 100′by any of a variety of methods, including varying the gas flow from aGCIB source supply; modulating the ionizer 122 by either varying afilament voltage V_(F) or varying an anode voltage V_(A); modulating thelens focus by varying lens voltages V_(L1) and/or V_(L2); ormechanically blocking a portion of the GCIB with a variable beam block,adjustable shutter, or variable aperture. The modulating variations maybe continuous analog variations or may be time modulated switching orgating.

The processing chamber 108 may further include an in-situ metrologysystem. For example, the in-situ metrology system may include an opticaldiagnostic system having an optical transmitter 280 and optical receiver282 configured to illuminate substrate 252 with an incident opticalsignal 284 and to receive a scattered optical signal 288 from substrate252, respectively. The optical diagnostic system comprises opticalwindows to permit the passage of the incident optical signal 284 and thescattered optical signal 288 into and out of the processing chamber 108.Furthermore, the optical transmitter 280 and the optical receiver 282may comprise transmitting and receiving optics, respectively. Theoptical transmitter 280 receives, and is responsive to, controllingelectrical signals from the control system 190. The optical receiver 282returns measurement signals to the control system 190.

The in-situ metrology system may comprise any instrument configured tomonitor the progress of the GCIB processing. According to oneembodiment, the in-situ metrology system may constitute an opticalscatterometry system. The scatterometry system may include ascatterometer, incorporating beam profile ellipsometry (ellipsometer)and beam profile reflectometry (reflectometer), commercially availablefrom Therma-Wave, Inc. (1250 Reliance Way, Fremont, Calif. 94539) orNanometrics, Inc. (1550 Buckeye Drive, Milpitas, Calif. 95035).

For instance, the in-situ metrology system may include an integratedOptical Digital Profilometry (iODP) scatterometry module configured tomeasure process performance data resulting from the execution of atreatment process in the GCIB processing system 100′. The metrologysystem may, for example, measure or monitor metrology data resultingfrom the treatment process. The metrology data can, for example, beutilized to determine process performance data that characterizes thetreatment process, such as a process rate, a relative process rate, afeature profile angle, a critical dimension, a feature thickness ordepth, a feature shape, etc. For example, in a process for directionallydepositing material on a substrate, process performance data can includea critical dimension (CD), such as a top, middle or bottom CD in afeature (i.e., via, line, etc.), a feature depth, a material thickness,a sidewall angle, a sidewall shape, a deposition rate, a relativedeposition rate, a spatial distribution of any parameter thereof, aparameter to characterize the uniformity of any spatial distributionthereof, etc. Operating the X-Y positioning table 253 via controlsignals from control system 190, the in-situ metrology system can mapone or more characteristics of the substrate 252.

In the embodiment shown in FIG. 8, the GCIB processing system 100″ canbe similar to the embodiment of FIG. 6 and further comprise a pressurecell chamber 350 positioned, for example, at or near an outlet region ofthe ionization/acceleration chamber 106. The pressure cell chamber 350comprises an inert gas source 352 configured to supply a background gasto the pressure cell chamber 350 for elevating the pressure in thepressure cell chamber 350, and a pressure sensor 354 configured tomeasure the elevated pressure in the pressure cell chamber 350.

The pressure cell chamber 350 may be configured to modify the beamenergy distribution of GCIB 128 to produce a modified processing GCIB128A′. This modification of the beam energy distribution is achieved bydirecting GCIB 128 along a GCIB path through an increased pressureregion within the pressure cell chamber 350 such that at least a portionof the GCIB traverses the increased pressure region. The extent ofmodification to the beam energy distribution may be characterized by apressure-distance integral along the at least a portion of the GCIBpath, where distance (or length of the pressure cell chamber 350) isindicated by path length (d). When the value of the pressure-distanceintegral is increased (either by increasing the pressure and/or the pathlength (d)), the beam energy distribution is broadened and the peakenergy is decreased. When the value of the pressure-distance integral isdecreased (either by decreasing the pressure and/or the path length(d)), the beam energy distribution is narrowed and the peak energy isincreased. Further details for the design of a pressure cell may bedetermined from U.S. Pat. No. 7,060,989, entitled “Method and apparatusfor improved processing with a gas-cluster ion beam”; the content ofwhich is incorporated herein by reference in its entirety.

Control system 190 comprises a microprocessor, memory, and a digital I/Oport capable of generating control voltages sufficient to communicateand activate inputs to GCIB processing system 100 (or 100′, 100″), aswell as monitor outputs from GCIB processing system 100 (or 100′, 100″).Moreover, control system 190 can be coupled to and can exchangeinformation with vacuum pumping systems 170A, 170B, and 170C, first gassource 111, second gas source 112, first gas control valve 113A, secondgas control valve 113B, beam electronics 130, beam filter 146, beam gate148, the X-scan actuator 160, the Y-scan actuator 162, and beam currentsensor 180. For example, a program stored in the memory can be utilizedto activate the inputs to the aforementioned components of GCIBprocessing system 100 according to a process recipe in order to performa GCIB process on substrate 152.

However, the control system 190 may be implemented as a general purposecomputer system that performs a portion or all of the microprocessorbased processing steps of the invention in response to a processorexecuting one or more sequences of one or more instructions contained ina memory. Such instructions may be read into the controller memory fromanother computer readable medium, such as a hard disk or a removablemedia drive. One or more processors in a multi-processing arrangementmay also be employed as the controller microprocessor to execute thesequences of instructions contained in main memory. In alternativeembodiments, hard-wired circuitry may be used in place of or incombination with software instructions. Thus, embodiments are notlimited to any specific combination of hardware circuitry and software.

The control system 190 can be used to configure any number of processingelements, as described above, and the control system 190 can collect,provide, process, store, and display data from processing elements. Thecontrol system 190 can include a number of applications, as well as anumber of controllers, for controlling one or more of the processingelements. For example, control system 190 can include a graphic userinterface (GUI) component (not shown) that can provide interfaces thatenable a user to monitor and/or control one or more processing elements.

Control system 190 can be locally located relative to the GCIBprocessing system 100 (or 100′, 100″), or it can be remotely locatedrelative to the GCIB processing system 100 (or 100′, 100″). For example,control system 190 can exchange data with GCIB processing system 100using a direct connection, an intranet, and/or the internet. Controlsystem 190 can be coupled to an intranet at, for example, a customersite (i.e., a device maker, etc.), or it can be coupled to an intranetat, for example, a vendor site (i.e., an equipment manufacturer).Alternatively or additionally, control system 190 can be coupled to theinternet. Furthermore, another computer (i.e., controller, server, etc.)can access control system 190 to exchange data via a direct connection,an intranet, and/or the internet.

Substrate 152 (or 252) can be affixed to the substrate holder 150 (orsubstrate holder 250) via a clamping system (not shown), such as amechanical clamping system or an electrical clamping system (e.g., anelectrostatic clamping system). Furthermore, substrate holder 150 (or250) can include a heating system (not shown) or a cooling system (notshown) that is configured to adjust and/or control the temperature ofsubstrate holder 150 (or 250) and substrate 152 (or 252).

Vacuum pumping systems 170A, 170B, and 170C can include turbo-molecularvacuum pumps (TMP) capable of pumping speeds up to about 5000 liters persecond (and greater) and a gate valve for throttling the chamberpressure. In conventional vacuum processing devices, a 1000 to 3000liter per second TMP can be employed. TMPs are useful for low pressureprocessing, typically less than about 50 mTorr. Although not shown, itmay be understood that pressure cell chamber 350 may also include avacuum pumping system. Furthermore, a device for monitoring chamberpressure (not shown) can be coupled to the vacuum vessel 102 or any ofthe three vacuum chambers 104, 106, 108. The pressure-measuring devicecan be, for example, a capacitance manometer or ionization gauge.

Referring now to FIG. 9, a section 300 of a gas cluster ionizer (122,FIGS. 6, 7 and 8) for ionizing a gas cluster jet (gas cluster beam 118,FIGS. 6, 7 and 8) is shown. The section 300 is normal to the axis ofGCIB 128. For typical gas cluster sizes (2000 to 15000 atoms), clustersleaving the skimmer aperture (120, FIGS. 6, 7 and 8) and entering anionizer (122, FIGS. 6, 7 and 8) will travel with a kinetic energy ofabout 130 to 1000 electron volts (eV). At these low energies, anydeparture from space charge neutrality within the ionizer 122 willresult in a rapid dispersion of the jet with a significant loss of beamcurrent. FIG. 9 illustrates a self-neutralizing ionizer. As with otherionizers, gas clusters are ionized by electron impact. In this design,thermo-electrons (seven examples indicated by 310) are emitted frommultiple linear thermionic filaments 302 a, 302 b, and 302 c (typicallytungsten) and are extracted and focused by the action of suitableelectric fields provided by electron-repeller electrodes 306 a, 306 b,and 306 c and beam-forming electrodes 304 a, 304 b, and 304 c.Thermo-electrons 310 pass through the gas cluster jet and the jet axisand then strike the opposite beam-forming electrode 304 b to produce lowenergy secondary electrons (312, 314, and 316 indicated for examples).

Though (for simplicity) not shown, linear thermionic filaments 302 b and302 c also produce thermo-electrons that subsequently produce low energysecondary electrons. All the secondary electrons help ensure that theionized cluster jet remains space charge neutral by providing low energyelectrons that can be attracted into the positively ionized gas clusterjet as required to maintain space charge neutrality. Beam-formingelectrodes 304 a, 304 b, and 304 c are biased positively with respect tolinear thermionic filaments 302 a, 302 b, and 302 c andelectron-repeller electrodes 306 a, 306 b, and 306 c are negativelybiased with respect to linear thermionic filaments 302 a, 302 b, and 302c. Insulators 308 a, 308 b, 308 c, 308 d, 308 e, and 308 f electricallyinsulate and support electrodes 304 a, 304 b, 304 c, 306 a, 306 b, and306 c. For example, this self-neutralizing ionizer is effective andachieves over 1000 micro Amps argon GCIBs.

Alternatively, ionizers may use electron extraction from plasma toionize clusters. The geometry of these ionizers is quite different fromthe three filament ionizer described above but the principles ofoperation and the ionizer control are very similar. Referring now toFIG. 10, a section 400 of a gas cluster ionizer (122, FIGS. 6, 7 and 8)for ionizing a gas cluster jet (gas cluster beam 118, FIGS. 6, 7 and 8)is shown. The section 400 is normal to the axis of GCIB 128. For typicalgas cluster sizes (2000 to 15000 atoms), clusters leaving the skimmeraperture (120, FIGS. 6, 7 and 8) and entering an ionizer (122, FIGS. 6,7 and 8) will travel with a kinetic energy of about 130 to 1000 electronvolts (eV). At these low energies, any departure from space chargeneutrality within the ionizer 122 will result in a rapid dispersion ofthe jet with a significant loss of beam current. FIG. 10 illustrates aself-neutralizing ionizer. As with other ionizers, gas clusters areionized by electron impact.

The ionizer includes an array of thin rod anode electrodes 452 that issupported and electrically connected by a support plate (not shown). Thearray of thin rod anode electrodes 452 is substantially concentric withthe axis of the gas cluster beam (e.g., gas cluster beam 118, FIGS. 6, 7and 8). The ionizer also includes an array of thin rod electron-repellerrods 458 that is supported and electrically connected by another supportplate (not shown). The array of thin rod electron-repeller electrodes458 is substantially concentric with the axis of the gas cluster beam(e.g., gas cluster beam 118, FIGS. 6, 7 and 8). The ionizer furtherincludes an array of thin rod ion-repeller rods 464 that is supportedand electrically connected by yet another support plate (not shown). Thearray of thin rod ion-repeller electrodes 464 is substantiallyconcentric with the axis of the gas cluster beam (e.g., gas cluster beam118, FIGS. 6, 7 and 8).

Energetic electrons are supplied to a beam region 444 from a plasmaelectron source 470. The plasma electron source 470 comprises a plasmachamber 472 within which plasma is formed in plasma region 442. Theplasma electron source 470 further comprises a thermionic filament 476,a gas entry aperture 426, and a plurality of extraction apertures 480.The thermionic filament 476 is insulated from the plasma chamber 470 viainsulator 477. As an example, the thermionic filament 476 may include atungsten filament having one-and-a-half turns in a “pigtail”configuration.

The section 400 of the gas cluster ionizer comprises anelectron-acceleration electrode 488 having plural apertures 482.Additionally, the section 400 comprises an electron-decelerationelectrode 490 having plural apertures 484. The plural apertures 482, theplural apertures 484, and the plural extraction apertures 480 are allaligned from the plasma region 442 to the beam region 444.

Plasma forming gas, such as a noble gas, is admitted to the plasmachamber 472 through gas entry aperture 426. An insulate gas feed line422 provides pressurized plasma forming gas to a remotely controllablegas valve 424 that regulates the admission of plasma forming gas to theplasma chamber 472.

A filament power supply 408 provides filament voltage (V_(F)) fordriving current through thermionic filament 476 to stimulatethermo-electron emission. Filament power supply 408 controllablyprovides about 140 to 200 A (amps) at 3 to 5 V (volts). An arc powersupply 410 controllably provides an arc voltage (V_(A)) to bias theplasma chamber 472 positive with respect to the thermionic filament 476.Arc power supply 410 is typically operated at a fixed voltage, typicallyabout 35 V, and provides means for accelerating the electrons within theplasma chamber 472 for forming plasma. The filament current iscontrolled to regulate the arc current supplied by the arc power supply410. Arc power supply 410 is capable of providing up to 5 A arc currentto the plasma arc.

Electron deceleration electrode 490 is biased positively with respect tothe plasma chamber 472 by electron bias power supply 412. Electron biaspower supply 412 provides bias voltage (V_(B)) that is controllablyadjustable over the range of from 30 to 400 V. Electron accelerationelectrode 488 is biased positively with respect to electron decelerationelectrode 490 by electron extraction power supply 416. Electronextraction power supply 416 provides electron extraction voltage(V_(EE)) that is controllable in the range from 20 to 250 V. Anacceleration power supply 420 supplies acceleration voltage (V_(ACC)) tobias the array of thin rod anode electrodes 452 and electrondeceleration electrode 490 positive with respect to earth ground.V_(ACC) is the acceleration potential for gas cluster ions produced bythe gas cluster ionizer shown in section 400 and is controllable andadjustable in the range from 1 to 100 kV. An electron repeller powersupply 414 provides electron repeller bias voltage (V_(ER)) for biasingthe array of thin rod electron-repeller electrodes 458 negative withrespect to V_(ACC). V_(ER) is controllable in the range of from 50 to100 V. An ion repeller power supply 418 provides ion repeller biasvoltage (V_(IR)) to bias the array of thin rod ion-repeller electrodes464 positive with respect to V_(ACC). V_(IR) is controllable in therange of from 50 to 150 V.

A fiber optics controller 430 receives electrical control signals oncable 434 and converts them to optical signals on control link 432 tocontrol components operating at high potentials using signals from agrounded control system. The fiber optics control link 432 conveyscontrol signals to remotely controllable gas valve 424, filament powersupply 408, arc power supply 410, electron bias power supply 412,electron repeller power supply 414, electron extraction power supply416, and ion repeller power supply 418.

For example, the ionizer design may be similar to the ionizer describedin U.S. Pat. No. 7,173,252, entitled “Ionizer and method for gas-clusterion-beam formation”; the content of which is incorporated herein byreference in its entirety.

The gas cluster ionizer (122, FIGS. 6, 7 and 8) may be configured tomodify the beam energy distribution of GCIB 128 by altering the chargestate of the GCIB 128. For example, the charge state may be modified byadjusting an electron flux, an electron energy, or an electron energydistribution for electrons utilized in electron collision-inducedionization of gas clusters.

Although only certain embodiments of this invention have been describedin detail above, those skilled in the art will readily appreciate thatmany modifications are possible in the embodiments without materiallydeparting from the novel teachings and advantages of this invention.Accordingly, all such modifications are intended to be included withinthe scope of this invention.

1. A method for silicide formation on a substrate, comprising:depositing a metal-containing layer over at least a portion of asilicon-containing substrate; irradiating said portion of saidsilicon-containing substrate with a gas cluster ion beam (GCIB)following said depositing of said metal-containing layer; and reacting aportion of said metal-containing layer with said portion of saidsilicon-containing substrate to form a silicide region, wherein saidreacting proceeds before, during or after said irradiating said portionof said silicon-containing substrate with said GCIB.
 2. The method ofclaim 1, wherein said silicon-containing substrate comprises singlecrystal silicon, poly-crystalline silicon, silicon-germanium (SiGe_(x)),silicon-carbon (SiC_(y)), or silicon-germanium-carbon (SiGe_(x)C_(y)),or any combination of two or more thereof, and wherein x and y aregreater than or equal to
 0. 3. The method of claim 1, wherein saidmetal-containing layer comprises tungsten, tantalum, zirconium,titanium, hafnium, platinum, palladium, vanadium, niobium, cobalt,nickel, or any alloy thereof.
 4. The method of claim 1, wherein saidmetal-containing layer comprises nickel or an alloy thereof.
 5. Themethod of claim 1, further comprising: increasing Si content at asurface of said portion of said silicon-containing substrate using saidGCIB, or another GCIB, or said GCIB and said another GCIB.
 6. The methodof claim 5, wherein said GCIB, or said another GCIB, or said GCIB andsaid another GCIB contain Si and optionally a noble gas element.
 7. Themethod of claim 5, wherein said increasing Si content precedes saiddepositing said metal-containing layer.
 8. The method of claim 1,wherein said GCIB comprises at least one element selected from the groupconsisting of He, Ne, Ar, Xe, Kr, B, C, Si, Ge, N, P, As, O, S, F, Cl,and Br.
 9. The method of claim 1, further comprising: infusing saidportion of said silicon-containing substrate with one or more atomicconstituents using said GCIB, or another GCIB, or said GCIB and saidanother GCIB, wherein said infusing is performed before, during, orafter said irradiating said portion of said silicon-containing substratewith said GCIB, and wherein said infusing comprises introducing one ormore elements selected from the group consisting of He, Ne, Ar, Xe, Kr,B, C, Si, Ge, N, P, As, O, S, F, Cl, and Br.
 10. The method of claim 1,further comprising: irradiating said portion of said silicon-containingsubstrate with another gas cluster ion beam (GCIB) preceding saiddepositing said metal-containing layer.
 11. The method of claim 10,wherein said another GCIB comprises at least one element selected fromthe group consisting of He, Ne, Ar, Xe, Kr, B, C, Si, Ge, N, P, As, O,S, F, Cl, and Br.
 12. The method of claim 1, further comprising:cleaning said portion of said silicon-containing substrate before orafter said irradiating with said GCIB and prior to said depositing saidmetal-containing layer.
 13. The method of claim 1, further comprising:depositing a titanium nitride (TiN) layer over said metal-containinglayer prior to said reacting said portion of said metal-containing layerwith said silicon-containing substrate.
 14. The method of claim 1,wherein said reacting said portion of said metal-containing layer withsaid silicon-containing substrate comprises performing a thermal annealprocess.
 15. The method of claim 1, further comprising: removing anun-reacted portion of said metal-containing layer from saidsilicon-containing substrate following said reacting said portion ofsaid metal-containing layer with said silicon-containing substrate;annealing said silicon-containing substrate following said removing saidun-reacted portion of said metal-containing layer from said substrate;forming a dielectric layer on said silicon-containing substrate oversaid silicide region; performing a contact etch process above saidsilicide region to open a contact via through said dielectric layer to acontact surface of said silicide region; and irradiating said contactsurface of said contact via with another gas cluster ion beam (GCIB) toetch said contact surface, clean said contact surface, dope said contactsurface, modify said contact surface, deposit material on said contactsurface, or grow material on said contact surface, or any combination oftwo or more thereof.
 16. The method of claim 1, wherein said irradiatingsaid silicon-containing substrate with said GCIB comprises: establishingsaid GCIB; selecting a beam energy, a beam energy distribution, a beamfocus, and a beam dose to achieve a desired thickness of a mixed layerformed during said irradiating said portion of said silicon-containingsubstrate with said GCIB; accelerating said GCIB to achieve said beamenergy; focusing said GCIB to achieve said beam focus; and exposing saidportion of said silicon-containing substrate to said accelerated GCIBaccording to said beam dose, wherein said beam energy ranges from about1 keV to about 60 keV, and said beam dose ranges from about 1×10¹²clusters per cm² to about 1×10¹⁴ clusters per cm².
 17. A method forsilicide formation on a substrate, comprising: irradiating at least aportion of a substrate with a gas cluster ion beam (GCIB) to modify saidportion of said substrate, wherein said portion of said substrateincludes a SiGe region or a SiGeC region; depositing a metal-containinglayer over said portion of said substrate preceding said irradiatingwith said GCIB or following said irradiating with said GCIB; reacting aportion of said metal-containing layer with said portion of saidsubstrate to form a silicide region; and increasing a proportion ofsilicon in said SiGe or SiGeC region using an Si-containing GCIBselected from said GCIB or another GCIB, wherein said increasing saidproportion of silicon precedes said depositing, precedes said reacting,or follows said reacting, or proceeds according to any combinationthereof.
 18. The method of claim 17, further comprising: amorphizingsaid SiGe or SiGeC region using said Si-containing GCIB to a depth ofbetween about 3 to 30 nm.
 19. A silicidation process, comprising:preparing a substrate with a SiGe_(a)C_(b) region, wherein a is greaterthan 0, and b is greater than or equal to 0; and irradiating at least aportion of said SiGe_(a)C_(b) region with a gas cluster ion beam (GCIB)to form a silicon-rich sub-layer at a surface of said SiGe_(a)C_(b)region to a depth ranging from about 3 nm to about 30 nm, saidsilicon-rich sub-layer having the composition SiGe_(c)C_(d), wherein cis greater than or equal to 0 and less than a and 1, and wherein d isgreater than or equal to 0 and less than b and
 1. 20. The method ofclaim 19, further comprising: amorphizing said at least a portion ofsaid SiGe_(a)C_(b) region using said GCIB to a depth of between about 3to 30 nm.
 21. The method of claim 19, further comprising: depositing ametal-containing layer over said substrate; and reacting saidmetal-containing layer with said silicon-rich sub-layer to form asilicide region in said substrate.